1. Technical Field
The present invention relates to an electro-optic device, a method for driving an electro-optic device, an electronics device, and the like.
2. Related Art
Heretofore, among display control circuits for electro-optic devices such as an organic EL device, there has been a display control circuit including a first output circuit having a high driving performance and including a dead zone and a second output circuit being capable of outputting a voltage with high accuracy and including no dead zone (for example, JP-A-2013-160872). When such a display control circuit drives an electro-optic device using a grayscale voltage having been selected from among a plurality of grayscale voltages on the basis of a set of display data, the display control circuit allows the first output circuit to drive an output terminal until the voltage level of the output terminal has reached a voltage near a grayscale voltage to be output. Thus, the display control circuit is capable of charging/discharging the output terminal at high speed. Further, when the voltage level of the output terminal has reached the voltage near the grayscale voltage to be output, the output of the first output circuit is brought into a high impedance state because the first output circuit enters its dead zone. At this time point, the output terminal has been charged/discharged up to the voltage near the grayscale voltage by the first output circuit, and thereafter, the output terminal is driven by the second output circuit. Thus, the second output circuit is simply required to be capable of charging/discharging a slight voltage remained to reach the target grayscale voltage. In this case, the second output circuit is capable of outputting a voltage with high accuracy, and thus, the required grayscale voltage is output with high accuracy. As described above, the output terminal is driven in a short time by the high-driving performance first output circuit up to the voltage near the target grayscale voltage, and thereafter, the output terminal is driven by the highly accurate second output circuit. Thus, this configuration not only enables the required grayscale voltage to be output with high accuracy, but also enables reduction of the power consumption.
To date, however, in a display driving operation using a plurality of output circuits each constituted by the high-driving performance first output circuit including a dead zone and the highly accurate second output circuit including no dead zone, a situation in which brightness differences appear among units of display each driven by a corresponding one of the output circuits and these brightness differences degrade the quality of display has sometimes occurred. The highly accurate second output circuit is constituted by transistors each having a large area, that is, having a long transistor-length, to reduce the variation of its output voltage. In contrast, the high-driving performance first output circuit is constituted by transistors each having a short transistor-length because, for this high-driving performance first output circuit, the increase of the operation speed is given more importance than the reduction of the variation. For this reason, the width of the dead zone of the first output circuit varies, and this variation causes the output voltages of the output circuits to differ from one another. Consequently, these differences among the output voltages have appeared as the brightness differences.